The maternal mortality ratio (MMR) is a significant indicator of the quality of a health care system. Despite considerable progress in reducing MMR in Iran in the past few years, we still face a long road ahead in eliminating preventable maternal deaths. In the present study, we evaluated all 80 cases of maternal deaths in 20 hospitals under the supervision of Tehran University of Medical Sciences between March 20 2013 and March 19 2020. During this time, these hospitals recorded 335,216 live births, with an MMR of 24 per 100,000 live births. The average age of deceased mothers was 31.9 ± 6.9 years. Direct causes accounted for 48.75% of maternal deaths, with haemorrhage being the most common direct cause of mortality (17.5%). Moreover, cancer (17.5%) and cardiovascular diseases (17.5%) were the most common indirect causes of maternal mortality. Even after accounting for the COVID-19 pandemic's effects, we have noticed an increase in maternal mortality. As a result, implementing a comprehensive approach for high-risk pregnancies is critical. Impact Statement What is already known on this subject? Although we have been able to reduce MMR in Iran to a reasonable level, previous measures would not be sufficient to accomplish future goals. Furthermore, we have a long way to go before reaching the ultimate goal of eradicating avoidable maternal deaths by 2030. What do the results of this study add? The causes, determinants and risk factors of maternal mortality were investigated in this study. With this level of detail, we can observe a steadily increase in MMR in recent years, regardless of the COVID-19 pandemic. The majority of pregnancy-related deaths can be avoided. What are the implications of these findings for clinical practice and/or further research? MMR reduction is a measurable goal that can be attained by improving financial resources, implementing safe delivery, team training, preparing multidisciplinary care with integration for high-risk pregnant women, establishing good provider relationships, and communicating with patients and providers for early warning signs and structural changes.